Apparatus for making venetian blind slats



Oct. 31 1961 J. l.. FRll-:DMAN

APPARATUS FOR MAKING VENETIAN BLIND sLATs Filed March 1s. 1952 4 Sheets-Sheet l flllll Iliff vllil. flll.

fill! fav IN V EN TOR.

Oct. 31, 1961 J. L. FRIEDMAN APPARATUS FOR MAKING VENETIAN BLIND SLATS Filed March 13. 1952 4 Sheets-'Sheet 2 Oct. 31, 1961 J. L. FRIEDMAN APPARATUS FOR MAKlNG VENETIAN BLIND SLATS Filed March l5, 1952 4 Sheets-Sheet 3 INVENTOR.

Oct. 31, 1961 J. FRIEDMAN APPARATUS FOR MAKlNG VENETIAN BLIND sLATs Filed March l5, 1952 4 Sheets-Sheet 4 INVENTOR.

United States Patent O "T 3,006,031 APPARATUS FR MAKENG VENETIAN BLIND SLATS Jay Leon Friedman, New York, N.Y., assignor to Artn craft Venetian Blind Manufacturing Company, St.

Louis, M o., a corporation of Missouri Filed Mar. 13, 1952, Ser. No. 276,269 4 Claims. (Cl. 1819) 'I'his invention relates generally to Venetian blinds and more particularly to flexible, resilient plastic (synthetic resin) slats and to a machine and process for manufacturing these slats.

While it has heretofore been proposed to make such slats of plastic, there have been subject to a number of disadvantages, such as excessive thickness and weight, insufficiency or absence of resiliency and translucency, and distortion including sagging and twisting.

It is therefore among the principal objects to provide slats wherein the foregoing disadvantages are reduced to a Another object is to provide slats which are light in weight so that in the blind they are easier to manipulate for tilting and elevating. This results in more lightly constructed supporting structure with consequent reduction in cost thereof.

Pre-stressed plastic sheet having certain characteristics, which make it unsuitable for the present purpose, is utilized as the basic material, and it is another object of the invention to overcome the characteristics by novel slat construction and fabrication.

A feature of the slats constructed in accordance with the present invention lies in the fact that they have a high degree of elasticity and resiliency, so that very severe distortions of the blind may be indulged in and upon release of external pressure or tension the slats return to their original shape and position.

A further object of the present invention lies in the provision of Venetian blind slat construction in which the slat is transversely bisymmetrically curved, whereby the slat offers greater resistance to sagging and distortion which otherwise tend to occur with the passage of time and at elevated temperatures.

Another object lies in the provision of apparatus and methods for the production of these slats.

These objects and other incidental ends and advantages will more fully appear in the progress of this disclosure and be pointed out in the appended claims.

In the drawings similar reference characters designate corresponding parts throughout the several views.

FIGURE 1 is a fragmentary perspective view of a Venetian blind showing an embodiment of the invention.

FIGURE 2 is a perspective view of one of the slats of FIGURE 1.

FIGURE 3 is a fragmentary view in perspective showing means and methods for making the slat shown in FIGURE 2.

FIGURE 4 is a fragmentary sectional view as seen from the plane 4-4 on FIGURE 3, with supporting structure omitted for clarity.

FIGURE 5 is an enlarged fragmentary sectional view as seen from the plane 5-5 on FIGURE 7.

FIGURE 6 is an enlarged fragmentary sectional view as seen from the plane 6 6 on FIGURE 7.

FIGURE 7 is a view in perspective of the heating element or steam box with the cover open. This corresponds generally to the lower central portion of FIG- URE 3.

FIGURE 8 is a fragmentary sectional view as might be seen from the plane 8.8 on FIGURE 3 with parts in an altered position.

3,006,031 Patented Oct. 3l, 1961 lCe FIGURE 9 is a fragmentary sectional view as seen from the plane 9-9 on FIGURE 7.

FIGURE 10 is a fragmentary sectional view as seen from the plane 10-10 on FIGURE 7.

FIGURE 11 is a fragmentary plan view of the forming element disposed in the right hand portion of FIGURE 7.

FIGURE l2 is a sectional view as seen from the plane 12-12 on FIGURE 11.

FIGURE 13 is a fragmentary view in perspective of' internal parts of the forming element.

FIGURE 14 is an enlarged sectional view as seen from the plane 14-14 on FIGURE 11.

In accordance with the invention, a Venetian blind generally indicated by reference character 10 comprises a head 11, tilting and supporting tapes 12 and 13, elevating cords 14 and 15, tilt cords 16 and 17, a bottom rail 18 and a plurality of slats 20. The head 11 may be in the form of an open or closed head rail and the other parts of the Venetian blind with the exception of the slats 20 may be of well known construction, so that a detailed description thereof is deemed unnecessary for the present disclosure.

As seen in FIGURE 2, the slat 20 has a top surface 22, a bottom surface 24, lateral edges 26 and 28 and end edges 30 and 32. The slat 20 may be provided with oriiices 34 and 36 through which the cords 14' and 15 may pass in a well known manner. The slat 20 has a transverse bisymmetric reverse curvature with three radii about three separate points, two disposed to one surface of the slat and the third disposed to the other surface of the slat. The slat 20 is composed of a substantially homogeneous material of .0l0 to .020 inch thick, which is a single organic polymer or a mixture of organic polymers. Among such polymers are vinyl compounds or derivatives, such as polystyrene, vinyl chloride and copolymer of or including such compounds or derivatives. Specically, but without being limited thereto, the invention contemplates the production of such slats from polystyrene.

I have found that while such materials present good stability when they are relatively thick, they are subject to the disadvantage then of high weight, cost, and light blockage. When slats are made of such materials of little thickness, that is to say, when the distance between the top surface 22 and the bottom surface 24 is of the order of .010 or .020 inch, I have found that they will not maintain desired shape and linearity unless the slats are pretensioned or given a temper by drawing the same when they are in a softened condition and are made bisymmetric with respect to the longitudinal axis thereof.

Such drawing or stretching of the material of which the slat is composed is preferably performed upon a wide web as disclosed in Patent No. 2,412,187 to Fred E. Wiley et al. for Process and Apparatus for Producing Continuous Sheet of Basically Oriented Organic Polymer, and from this wide web a strip of the desired width is cut. This basically oriented sheet of Wiley et al. is a unique material which has an elastic memory of stretch in two directions. When it is slit into strips and made into slats of non-bisymmetric transverse form, the resultant product is unsatisfactory. Because of relatively Wide reaches between the tapes 12 and `13, there is a tendency for the long strip to twist when formed as a slat, but the tendency to twist is prevented to a satisfactory degree by the construction of the slat in a bisymmetrically reverse curve shape. This is seen in FIGURES 2 and 6, where the slat 20 has (as viewed from above) a pair of balanced convex curved portions 37 and 38 and a concave curved portion 39 disposed between the portions 37 and 38. This bisymmetric reverse curvature balances any undesirable strains in the material of which the slat 20 is composed so that the slat maintains its shape in use.

FIGURE 5 shows a cross section of a web or band of organic polymer such as polystyrene preferably substantially .015 inch thick, generally indicated by reference character 4 0, which comes off ina substantially continuous strip from the coil 41 and is fed in the direction of the arrow 42 by the primary feed rolls 44 and 46. The primary feed rolls 44 and 46 operate to feed the band 40 between them at a predetermined rate of speed. These rolls may be power driven by suitable means not shown, The primary feed rolls 44 and 46 and the secondary feed rolls 103 and 104 may all be driven and contoured as shown, or one roll in each pair may be power driven and the other a spring pressed idler. Since the primary and secondary feed rolls engage the formed slat strip 100 which is resiliently attenable, they may be fiat surface cylindrical rubber rolls.

The band 40 is drawn from the coil 41, which is mounted on an axle 45, into the cleaning, lubricating and coating element 61, about the idler pulleys 50, 51 and S2 through the bath 53 in the tank 54. Suflicient frictional drag on the coil 41 is desirable to prevent free wheeling or sag of the band 40 while in the heating element. The pulleys 50, 51 and 52 are Ijournalled between the plates 55 and 56 of the carrier frame of the grinding unit 57, which rests in the tank 54 and may be elevated for threading the band 40 therethrough (see FIGURE 8). Associated with the pulley 52 is a bath wiper element 58 which includes an absorbent member 59 mounted on the inverted U-shaped support 60 and adapted to take excess moisture from the band 40 as it leaves the pulley 52 on its way to the heating element 62, preferably in the form of a steam box.

Upon emerging from the cleaning, lubricating and coating step the band 40 is drawn through the entrance opening 65 into the heating element 62, which includes a casing 63 having a movably mounted cover 64, where it is subjected to steam at atmospheric pressure, which raises the temperature of the strip suihcient to soften it Y for forming it to have a bisymmetric curvature.

The softening step requires a substantial period of time, and depending upon the speed of travel of the band through the steam box, the length of the box may be determined. Said heating element has several steam pipes 66 and 67 with a plurality of jets 68 and 69, through which steam coming from a source (not shown) is ejected in the direction in which the band 40 is moving, parallel to said band, to maintain a continuous live steam atmosphere about the upper and lower surfaces of the band 40.

After passing the `second or last of the steam pipes the band has the condensed steam wiped by the first of a plurality of wipers, 70, 71 and '72 which may be substantially identical and preferably composed of a pair of pieces of absorbent sponge-like material (see FIG- URE 10), 73 and 74. The wiper member 7.1 may, for example, comprise upper and lower wiping members 75 and 76, upper and lower plates 77 and 78 and supports 79 which mount the wipers 70 and 71 on the floor of the casing 63. Condensation flows from the casing 63 through a suitable drain (not shown).

After leaving the wiper 70, the band is approximately at or slightly below the temperature of the steam and is soft enough to be formed but is not at high enough temperature to lose its biaxial orientation, and the band enters the forming element 80 (FIGURES 7 and 11-14). Element 80 includes edge forming members 81 and 82 which smooth and support the band 40 at its edges and converge from block 87 to block 88 and are thereafter parallel till exit 83, a central concavity or groove forming member 84 and outer convexity or bulge forming members 85 and 86, the general cross sectional shape of which is best seen in FIGURES 13 and 14. The members 81, 82 and 84 are preferably composed of sheet metal with smooth inner surfaces; members 81, 82, 85 and 86 being carried by lower support blocks 87, 88 and 89 resting on ledges 90 and 91 of the casing 63; and member 84 being carried by support piece 92 and upper support blocks 93, 94 and 95. The member 84 is removable and is aligned by suitable means such as dowels 96. The front ends 99 and 101 of the members 8S and 86 are rounded and tapered while the front end l101 of the member 84 converges downwardly over a substantial portion of its length to gradually form the hot band 40 into the slat strip 100. The member 84 converges downward from block 93 to block 94 and then is parallel to members 81, 82, 85 and 86 to block 95.

In the performance of the present process, it is to be noted that although the heated band 40 is soft, it is not accid and it has sufficient shape holding properties to permit it to be formed by continuously bending it about longitudinal axes and by contacting it along limited lineal areas of its surface. This permits reduced friction, bunching or marring of the strip as it passes between the members 81, 82, 84, 85 and 86. Furthermore, while being formed, its condition is such that upon leaving the rear end 115 of the forming element 80, it tends to return toward its previous flat state, and this is accommodated by over forming (compare FIGURE 14 and FIG- URE 6). The relatively long area of the forming element between blocks 94 and 95, which is preferably at least 150% as long as the area between blocks 93 and 94, holds the band 40 in proper shape as it begins to cool, and provides for proper set of the slat strip 100.

Since the heat source the steam jets 68 and 69, are located away from the exit 83, the band 40 as it emerges from the exit 83 is cooled at room temperature and becomes sufficiently set to hold its shape during its linal wiping at the weighted wiper 72, so that the primary feed rolls 44 and 46, the secondary feed rolls 103 and 104 and the transfer wheel 105 (a large idler driven by the Slat strip) do not permanently distort said strip.

The secondary feed 4rolls are driven by a power source not shown, and send the slat strip beneath a plurality of elevating cord hole punches, only one of which 106 being shown, since their number will vary with the length of the nished slat, and beneath a cut-off punch 107. When the end 108 of the slat strip 100 presses the trigger stop 109 it closes an electrical circuit 111 through the switch 110 to an actuator 112, which moves the crank Y 113 operating the cams 114 which depress the punches 106 and 107 to complete the slat 20. The secondary feed rolls only frictionally eng-age the slat strip 100 and momentarily slip while the strip is stationary during the action of the punches 106 and 107.

When the strip 100 is stopped for punching the excess strip loop out, see FIGURE 4, so that the forming at the forming element is continuous with uniformity assured.

It may thus be seen that there has been provided a novel Venetian blind slat construction which by virtue of the thinness of the slats and their composition may provide a translucent blind, which permits glareless illumination in the room where the blind is located. Because of the described construction, the slats are durable, cxble and resilient and because of the means and methods of making the same can be fabricated in large quantity economically, so that they may be used in the place of blinds lacking these desirable qualities. i

I wish it to be understood that I do not desire to be limited to the exact details shown and described in this speciiication, for obvious modifications will occur to a person skilled in the art to which the present invention pertains.

' I claim:

1. A machine for making thin, narrow, elongated, transversely bowed, plastic slats of thermoplastic strip material suitable for use in Venetian blinds or like articles, comprising: means to draw a strip of stilf but exible molecularly oriented thermoplastic material in an axial direction and to feed it lengthwise through heating means and forming means to be defined herein; a heating means for the strip, located in the path of its feed, said heating means being adapted to raise the temperature of the strip to a degree enabling it to be given a permanent non-planar cross sectional shape but not high enough to destroy its molecular orientation or to render it accid; a forming means in the path of the feed into which the strip is yfed from the forming means comprising opposed, elongated, lateral, edge-conning forming members on opposite sides of the strip path, each being shaped in the form of an angle with the apex o-f its inner side adapted to engage the edge of the strip, with one side below the edge of the strip yand the other side diverging upwardly from the top of the strip, the members facing one another so that they together provide a groove through which the strip must pass, the forming members having their entrance ends spaced apart suiciently to freely receive the strip, but having the lateral space between their edge engaging inner corners thereafter reduced so that the Width of the groove is less than the Width of the strip, to bow the strip transversely and to give it a non-planar cross section but not to bend it into a sharp corner, the yforming means having a length, in the direction of travel of the strip, sufliciently great to form the warm strip, and having an additional length suiliciently great to hold the edges of the strip in connernent and the strip bowed, so yas to enable the material to set in its non-planar shape.

2. The machine of claim 1, wherein the forming means has also an intermediate forming member, between the other two, to deect the mid portion of the bowed strip in a direction opposite the bowing, whereby to impart an M-shaped effect to the strip.

3. The machine of claim 1 wherein there is a stop removably disposable into and orut of the path of the strip subsequent to and spaced in advance of the forming means by a `distance greater than the length of strips to be cut, as hereinafter provided; cutting means spaced back from the stop a distance sullcient t0 provide a desired strip length between itself and the stop, but spaced beyond the forming means and feeding means suiciently to enable the strip to loop outwardly from its feed path when the stop is in position and the cutting means is operated.

4. The machine of claim 3, wherein there are additional strip punching means between the stop and the cutting means.

References Cited in the le of this patent UNITED STATES PATENTS 2,103,271 Pratt Dec. 28, 1937 2,229,225 Schneider Jan. 21, 1941 2,262,550 Hunter Nov. 11, 1941 2,294,434 Wilson Sept. 1, 1942 2,323,862 Zimmerman et al lluly 6, 1943 2,313,111 Wilson Mar. 9, 1943 2,319,099 Abramson May 11, 1943 2,412,187 Wiley et al Dec. 3, 1946 2,454,194 Maynard Nov. 16, 1948 2,526,945 `Gray Oct. 24, 1950 2,607,074 Slaughter Aug. 19, 1952 2,717,423 Uhlig et a1. Sept. 13, 1955 

